Along with Azerbaijan, Israel, Iceland, Sweden, South Africa, Portugal and Poland became the last founding members as of Wednesday, according to a statement issued by the Chinese finance ministry. 

The AIIB, which aims to fund infrastructure projects in Asia, is widely viewed as a potential counterbalance to U.S.-led multilateral lenders, such as the Asian Development Bank. 

The U.S. has expressed concerns about the AIIB's governance structure and decision-making process. 

China has offered $50 billion to the bank, which is expected to start operations by the end of this year, with other member nations expecting to increase the total amount of funding to $100 billion. 

The state-run China Daily reported on Tuesday that the AIIB's Asian members may have 75 percent of the voting rights, while the remaining 25 percent could go to non-Asian members. 

"While the bank's shareholding structure is subject to negotiation, there will be different arrangements for Asian members and non-Asian members," the report said, without saying where it gets the information. 

"One option is for the bank's Asian members to have 75 percent of the voting shares, with the right of each of those members potentially depending on the size of their GDP. The remaining 25 percent of the voting shares would then go to non-Asian members," it said.